Surface diffusion of hydrogen on Ru(001) studied using laser-induced thermal desorption

Abstract

The surface diffusion coefficient for hydrogen on Ru(001) at low coverage was measured using laser-induced thermal desorption techniques. In the temperature range between 260 and 330 K, the diffusion coefficients displayed Arrhenius behavior with an activation barrier Ediff=4.0±0.5 kcal and a preexponential factor D0=6.3×10−4 cm2/s. Agreement between the experimental and theoretical parameters suggests that hydrogen diffuses on the surface by moving from a threefold site to a neighboring threefold site via a twofold site. Surface contaminants such as carbon and oxygen were observed to produce dramatic effects on the hydrogen surface diffusion rate.

Hydrogen adsorption on Ru(001) studied by scanning tunneling microscopy

“…The diffusion of hydrogen on Ru(001) was studied extensively in the past by Mak et al [21][22][23]. The findings of these papers can be extrapolated to our temperature regime to give a diffusion coefficient value of ~5×10 -15 cm 2 s -1 , corresponding to a random walk distance of approximately 5 to10 lattice sites per second in the 54 K to 73 K temperature range.…”

Understanding the lateral movement of particles adsorbed at a solid–liquid interface

“…A mathematical scheme for calculating the surface diffusion coefficient on a heterogeneous surface has been reported, however conclusive experimental data in support of the model was not provided [1,2]. An experimental scheme to study the diffusion of molecules adsorbed on a solid surface has been reported [1][2][3][4] but the procedure is tedious and the obtained numbers are not consistent across different systems. It is possible that the lateral movement of the particles adsorbed at the solid-liquid interface is the rate-determining step for the process of electrostatically http://dx.doi.org/10.1016/j.jcis.2015.04.062 0021-9797/Ó 2015 Published by Elsevier Inc. driven particle adsorption at the solid-liquid interface.…”

Hydrogen Transfer on Metal Surfaces

“…In 1972, Ertl and Neumann introduced the laser-induced thermal desorption technique to determine the rate of diffusion [39]; later, this method was further refined by Seebauer and Schmidt [40] and Mak and collaborators [41][42][43]: In principle, the technique is based on the hole refilling' phenomenon and is relatively straightforward: A laser beam of known cross section is incident on an adsorbatecovered, well-defined patch on the surface, whereby the power of the laser beam is just sufficient to thermally desorb all the particles in the illuminated area. After the laser shot, refilling of the hole from the cold, H-rich surrounding sets in, which can be followed as a function of time by subsequently fired laser pulses into the same spot.…”